The present disclosure relates to process variable transmitters used in process control and monitoring systems. More specifically, the present disclosure relates to performing loop current diagnostics to identify on-scale errors in the loop current of a transmitter.
Process variable transmitters are used to measure process parameters (or process variables) in a process control or monitoring system. Microprocessor-based transmitters often include a sensor, an analog-to-digital converter for converting an output from the sensor into a digital form, a microprocessor for compensating the digitized output, and an output circuit for transmitting a compensated output. Currently, this transmission is normally done over a process control loop, such as a 4-20 milliamp control loop, or wirelessly.
Typically, in a 4-20 milliamp process instrument, the control loop is controlled by a loop current regulator. A loop current regulator regulates the loop current to reflect process variables sensed by the sensors in the instrument.